The specific and quantitative detection of deoxyribonucleic acid (DNA) is of great significance in a range of applications, from disease diagnostics to the recognition of lethal bio-toxins. Recent development in nanotechnology enables us to develop new detection systems with sensitivity down to a single molecular level. Detection of single DNA hybridization event may give us the opportunity to recognize gene sequences with extremely high accuracy. In recent years, gene microarray technology has exhibited special promise due to the levels of expression of thousands of gene fragments that can be measured simultaneously. However, current gene chip technology is mainly based on fluorescence readout and requires highly precise and expensive instrumentation, limiting its use to research laboratories.
Polymerase chain reaction (PCR)-based detection of DNA markers is replacing traditional techniques such as Southerns for the presence of disease marker, or time-consuming culture methods or serological techniques for bacterial or viral detection. Discovery and development of PCR techniques has given rise to a wave of kits for various purposes that come with perishable enzyme and nucleotides with buffers and primers. Many of these components are perishable, thus limiting their shelf lives. In addition, PCR is time-consuming. Though real-time PCR machines are on the market, they are expensive and far from being portable. When kits are not available, the detection usually requires skilled personnel to configure the reactions and perform the necessary analysis with appropriate controls.
The more recent fluorescent-based techniques such as fluorescent in situ hybridization (FISH), immunohistochemical stain (HercepTest), chromogenic in situ hybridization (CISH), single-molecule photon based detection and quantum dot-mediated two-color fluorescence coincidence detection still require skilled personnel, and expensive equipment and supplies. Use of these tools is limited to select individuals and/or organizations with access to sophisticated laboratories.